Method of coating cans



June 15, 1937. c. J. AULBACH ET AL METHOD OF COATING CANS Filed Feb. 13, 1956 gzarles J2 Amanda/$ x231 Ami-z;

. Patented June .15, 1937 PATENT OFFICE mn'rnonor COATING CANS Charles J. Aulbach' and Earl A. Herrig, Syracuse, N. Y., assignors to Continental Can Company, Inc., New YorkyN. Y., a. corporation of New York ApplicationFebruary 13, 1936, Serial No. 63,809 1 Claim. (Cl. 91-68) The invention relates to newand useful immovements in a method of providing a canwith a thermoplastic coating such as wax.-- An eflicient way of applying a coating of a thermoplastic ma- 5 terial to the interior of a can'is to reduce said material to liquid form and flood the interior surface of the can with said material while the can is inverted, and allowing the surplus material to drain from the can. During the draining, the i wax adheres to the metal and will flow around on to the under face of the lip-of thenozzle, thus producing a relatively thick coating of wax on-the outer face of the lip, which is objectionable, for the reason that when the sealing pressure ofthe l gasket is applied thereto, it is likely to craze and cleave from the metal.

An object of the invention is to provide a method whereby the wax accumulating on the outer face of the lip of the can nozzle during draining may be stripped or removed therefrom.

without, in any way, disturbing the coating covering the edge of the nozzle mouth.

In the drawin Figure 1 is a view showing a portion of a can with the wax drained therefrom and also showing the wax collecting on the outer face of the nozzle lip during draining;

Fig. 2 is a view similar to Fig. 1, but showing the wax stripped or removed from the outer face of the nozzle lip;

' Fig. 3 is a view showing the nozzle of the can with the wax stripped from the outer face of the lip and the can closed by a crown cap;

Fig. 41s a view showing more or less diagrammatically and in section a portion of an apparatus which may be used for applying a thermoplastic coating to the interior of the can; and

Fig. 5 is a view showing more or less diagrammatically a portion of an apparatus which may be used for stripping or removing the accumulated wax from the outer face of the nozzle lip.

The improved method has to do with the coating of a can provided with a nozzle which is closed by a cap, and a brief detail description will be given of the can nozzle and the manner of closing the same.

The can which is indicated at i is provided with a nozzle 2 having an inturned portion 3 surrounding an openingl throughwhich a can maybe filled and emptied. The inturned portion 3 at its free edge is turned downwardly and inwardly as indicated at 5. The nozzle is shaped so as to provide a shoulder 6. The can is closed by means of a cap 1 having a sealing gasket 8 disposed within the same which is adapted toengage the outer face 9 of the nozzle lip. This crown cap ispreferably crimped and bent underneath the shoulder 6 as indicated at ill.

The first step in the method consists in the applying of a coating of a thermoplastic materialsuch as wax to the interior of the can. In Fig. ,4, there is illustrated one form of apparatus which may be used for accomplishing this result. The can is inverted and is supported during coating by fingers ii carried by a traveling support ii.

A nozzle i3 is raised into the can as it travels for the purpose of supplying the coating material to the interior of the can. The can during travel preferably moves over a coating bath, and means '15 is provided for supplying the nozzle with a coating material in fluid form, under pressure, that as it flows from the upper end of the :nozzle it will v flood the entire inner surface of the can and will v drain from the nozzle back into the tank. The

coating machine which has just been referred to briefly, is shown and described in detail in the application of Alfred L. Kronquest, Serial No. 56,740, filed December 30, 1935. The particular way ofcoating the can forms no part of the pres- 3 eat invention, except for the fact that the can is flooded with the thermoplastic coating material while in liquid form and allowed to drain from the can. As the wax coating drains from the can, it

will adhere to the metal and will flow around on 30 to the outer face of the nozzle lip. In Fig. 1 of the drawing, a portion of the nozzle of the can is shown, and the coating is indicated at it. The portion of the coating adhering to the outer face of the nozzle lipis indicated at Ma.

After the can has been coated and drained sufflciently to leave a proper, thickness of coating on the interior of the can, it is then subjected to the next step inthe method forming the present invention where this surplus and undesirable 4ocoating material a onthe outer face of the nozzle lip is removed. is preferably accomplished by'placing theca'n while it is still in-' verted and the coating material is in flowing form over a pipe i5. Thecan is so supported on 4 a ledge ii that the inturned portion of the nozzle 5 forming the nozzle lip is out of cone tact with the pipe i5. This pipe I!) is mounted on a support I! and a port i8 formed in'the support leads to a that at the proper time, the pipe I! may be placed under a vacuum pull so that air 'will be drawn from the can. As the vacuum pull continues, air will flow in between the lip of the nozzle and the outer end of the pipe into the 5 vacuum creating means, s0 50 can and out through the pipe, and this creates a stream of air across the nozzle lip I.

The stream of air flowing inwardly across the outer face of the nozzle lip will take. up the thermoplastic material and carry it along in the air stream. This will gradually thin the coating an and equally spaced therefrom, the stream oi"v air will operateat the same time on all portions of the coating on the nozzle lip, and thus the coating will be quickly stripped from the nozzle.-

The portion of the apparatus shown in Fig; 5, for removing the coating from the nozzle, is shown and described in full oi showing one way of carrying out the method.

When the crown cap is applied to the nozzle for closing the can, the sealing gasket 0 contacts 9 of the nozzle lip. If the wax was allowed to remain on said outer face, as indicated in Fig. 1, the pressure of the sealing gasket against the wax coating would cause it to crack and when the cap is removed, the wax will cleave oil and this, of course, is very objectionable. However; when the wax is stripped from the outer face of the nozzle by the method above described, then the sealing gasket contacts directly with the metal at the outer face of the nozzle lip. The gasket will make 'sumcient contact with the coating at as to prevent the contents with the outer face of the can reaching the means may be provided for n I 'allowing the, surplus warm -air streamdsidirectcd across in an application'of Alfred L. Kronquest and Charles J. Aulbach, Se-

a the can, draining-the the thinned edge la so metal at the same time there will 01' the gasket on'the of It will. bewildermd the draining thereof from the can. and for removing or striml he wax face of the nomle liptj' 'Ihcementiai the invention reside in the method of can with athermoplastic coating i'romflthe camand then Jecting face of the nonlelipto an'air remove or strip allof the wax face of 'thenozzleilip. It is essential that wax shall be in a flowing condition wlmn preferably the operation oi removing was fol- The method zle provided with a lip, teriai consisting in flowing whileinliquid-torm over thecoatlng material the inner surface of o I lm'plus material therefrom, placing said can while the con; "-ie in flowing-"form-over a pipein alinement with the center of the nozzle and with the spaced .a. short distance fron the v pipe and connecting said pipeto a vacuum cresting means for drawing alr'through the pipe and across the face of the lip of the nozzle for removing the coating collecting thereon during draining.

V CHARLIS J. Ami-BACK.-

EARL A. HIRRIG.

of coating, cans, ha ing'a noz-J with a thermoplastic ma- 

